Technical Abstract:
Fumonisin mycotoxins are produced by Fusarium verticillioides, a fungus commonly found in corn. Their health effects in humans are not known, however, recent findings suggest that they might be a risk factor for neural tube defects (NTDs) in populations consuming large quantities of contaminated corn. Fumonisin B1 (FB1) was not teratogenic when given orally to pregnant CD1 mice during gestation days (GD) 7-15. Intraperitoneal injection of > 5 mg/kg body weight FB1 to pregnant mice of the inbred LM/Bc strain on GD 7.5-8.5 caused NTDs in the fetuses. To compare the susceptibility of these strains to fumonisin-induced NTDs, female LM/Bc and CD1 mice were fed diets containing 0 (control), 50 or 150 ppm FB1 (provided by F. verticillioides culture material) beginning 5 weeks before mating to unexposed males. The pregnant females and their fetuses were examined after GD16. Microscopic examination of the livers established that the 150 ppm diet was maternally toxic to both strains, however, no significant effects on fertility and litter size were noted. No NTDs or evidence of fetotoxicity was found in LM/Bc or CD1 groups fed the control or 50 ppm diets. At 150 ppm, one of five (20%) LM/Bc litters was positive for NTDs. While no NTDs were found in fetuses of the CD1 group fed 150 ppm, fetotoxicity occurred in two high-dose CD1 litters; the incidence of dead fetuses therein ranged from 40 to 64%. These findings suggest that the dietary no observed effect level for NTDs in the LM/Bc strain is > 50 ppm FB1, NTDs develop at maternally toxic doses, and strain-dependent differences in sensitivity to fumonisin-induced fetotoxicity and NTDs exist.